Physics ball sticks to a wall if moving slow

I've been banging my head on creating a realistic movement for a simple Pong game. After hours of trying to make the whole solid sprites + bullet ball idea to work properly I finally gave up and started doing it with physics. There was a huge improvement and the ball seems to bounce very realistically. However, for some reason if it's moving too slow it will stick to a wall.

Here's an example, just run it and wait for the ball to hit a wall at a sharp angle.

https://www.dropbox.com/s/0p5z1jvngoe1k ... .capx?dl=0